Surveillance applications usually require recording of all media (video/audio) for later access and retrieval for forensic purposes. Because of constant recording and need to keep archives for a long period of time, such as thirty days to three months or more, today's surveillance system needs either a large amount of videotapes for analog based system, or large amounts of disk space for digital recording and archive systems.
Conventional analog surveillance systems use analog signals to transmit, display, and record on analog-signal-based devices, and they store media archives in long-hour time-lapse tapes. A human expert is required to manage tapes and search and retrieve them manually. In contrast, a digital surveillance system converts analog signals to digital signals and encodes them to compress the data. Since encoding mechanisms are different, sizes of data vary according to the type of encoding process.
Digital surveillances are not only used in a variety application fields, but also have different needs relating to video content in terms of video encoding quality, storage efficiency, and others. Most digital surveillance systems offer only one, or very few, limited media encoding mechanisms.
Some problems of existing, conventional analog surveillance systems is that these systems do not enable convenient archive operations and are very time-consuming for searching and browsing a particular event video from storage archives.
Problems of existing, fixed-encoding-mechanism digital surveillance systems include: (a) a digital surveillance system records video using a fixed constant media rate regardless of the importance of a situation, thus consuming great amounts of storage space; (b) there are no content-based indexing and search systems to locate the target video efficiently; (c) a system provides only one type or very limited and pre-fixed types of media encoding methods; (d) there is no intelligence in encoding mechanism determination, such that manual operation is required to change the encoding type settings; and (e) the stored media is purged to tape or simply deleted if the disk space is full.
For long running operation, the disk space is always near full; therefore, the system needs to continue to purge or delete the media to make space available for new recordings.
An ideal digital surveillance system shall provide dynamic and scalable encoding and indexing methods that are needed based on alarm/event situations and/or actual video contents. The present invention, termed herein an Intelligent, dynamic, long-term digital Surveillance Media Storage System (ISMS), is a long-term digital media storage system with intelligent decision making based on event and content semantics to dynamically select the encoding method for new recording based on application defined priority and accuracy requirements. At the same time, it also, dynamically selects and converts previously recorded media to a less accurate recording format based on time and relative priority between a set of candidate media files and thus, forms a multistage media data compression mechanism that can best reduce the total storage size iteratively. This method traces computing resources with the storage resource to reduce the total system cost. The ISMS system can analyze contents and metadata of media streams, can provide flexible, scalable, and self-adjustable encoding and indexing mechanisms based on user defined rules, and can optimize the media storage in multiple stages according to time and semantically importance factors for digital surveillance systems. The system can include several subsystems, such as: (1) a media stream retriever/receiver; (2) a content-based description generator; (3) an intelligent engine; (4) an event handler; (5) a media stream writer; (6) a search and retrieval engine; (7) domain knowledge profiles; and (8) media file and metadata description index storage.
Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention.